EXCAVATOR

PROBLEM TO BE SOLVED: To further strongly attach a pilot bit portion and an enlarged diameter bit to a main body of an excavator in which the pilot bit portion is attached to the front end of the main body and the enlarged diameter bit is attached to the rear end of the same. SOLUTION: An excavator main body 11 having an almost multi-stepped columnar shape which stepwise enlarges in diameter toward the front end thereof, has a cutting blade attached to the front end thereof, to form a pilot bit portion 14, and an installing portion 13 formed on one side of the pilot bit portion 14 closer to the rear end, and a ring-shaped installing member 24 is fitted on the periphery of the installing portion 13 from the rear end, whereby the installing member 24 is installed on the main body 11 in one body. Then, enlarged diameter bits 28 each having a cutting blade attached to the front end of a bit main body 28A are installed at respective locations between the front end of the installing member 24 and a rear end surface 14B of the pilot bit portion 14, in a manner being supported by the pilot bit portion 14 and the installing member 24 and being rotatable on center axes X which are decentered from an axial line O of the main body 11 toward the periphery of the same.